$21$ is what percent of $700$ ?
Solution: Having a percent of something means that you get that percent out of every $100$ We can set up a proportion to find out what percent of $700$ we need to take to get $21$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We are trying to find the ${\text{percent}}$ . Is $700$ the ${\text{part}}$ or the ${\text{whole}}$ The $700$ is the ${\text{whole}}$ . This means the ${\text{part}}$ is $21$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{21}}{{700}}$ If we divide the denominator of the fraction on the right by $7$ , it will be the same denominator of the fraction on the left. To keep things equal, let's also divide the numerator on the right by $7$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{21 \div 7}}{{700 \div 7}}$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{3}}{{100}}$ $ {\text{percent}} = {3}$ So $21$ is $3\%$ of $700$.